Question

Forgive me if this is a particularly stupid question!

mysql_query($query)

returns a boolean, but you can also assign it to a variable

$results = mysql_query($query)

and then use the other mysql_ functions to extract data.

Out of curiosity, how does mysq_query($query) act as both a boolean and a data container at the same time? What’s happening “under the hood” during these steps?

(yes, I am a n00b…, please be kind!)

Answer 1

If you notice, when it returns true/false, you can’t use it with the other functions such as mysql_fetch_assoc().

From the mysql_query() documentation:

For SELECT, SHOW, DESCRIBE, EXPLAIN
and other statements returning
resultset, mysql_query() returns a
resource on success, or FALSE on
error.

For other type of SQL statements,
INSERT, UPDATE, DELETE, DROP, etc,
mysql_query() returns TRUE on success
or FALSE on error.or FALSE on error.

What happens, is for statements that do not return data, it responds true/false on whether or not the query was successful.

When there is a result set, you will see it returns a MySQL resource. This is a special value that allows PHP to figure out what data set you are talking about. You then pass this resource to other MySQL function to retrieve the data.

See: http://www.php.net/manual/en/language.types.resource.php